Since the 17-50mm lens is a Di-II lens (designed for use on APS-C size imaging sensors), you will need to multiply the focal length by a factor 1.56 to get the full frame equivalent (26-78mm). This also means that when the lens is used with a full frame sensor, you will see vignetting (since it was designed for a smaller sensor size). My Nikon D3 SLR automatically compensates for this limitation by “graying out” that part of the viewfinder. Through some clever photographing, I was able to capture the view through the viewfinder so you can see what it looks like:

The focal length range on the 17-50mm lens does lend itself to flexibility. While traveling throughout Tennessee for a speaking engagement, I actually photographed exclusively with the Tamron 17-50mm lens.

While on my trip, I also stopped at a world-famous barbeque restaurant. Yes, I did photograph my meal. The Tamron 17-50mm did a nice job of capturing my pulled pork sandwich while letting the busy background fall out of focus.

To test the VC feature (image stabilization), I first photographed my cat. Incidentally, this also pushed the minimum focus distance … as he was curious about the Tamron lens, too! I had the focus set on manual for this exposure, and positioned the camera as close to the cat as possible. Notice how his eyes are in focus, but his nose falls out of focus because it is too close.

This next comparison should give you a better sense of the effectiveness of the lens’s image stabilization mechanism. First, the “full” image:

And below is a close-up comparison: both were hand-held, same settings, except one had VC turned on. Can you guess which? And just so you know, I do consider myself to have a pretty steady hand when it comes to hand-holding at slow exposures. So it was definitely interesting to see these results—I’m convinced!

This full-featured 17-50mm lens weighs in at 21.15 ounces (570 g), and is available with lens mounts for both Canon and Nikon (with built-in AF motor). I was impressed at how lightweight the lens was, especially considering the VC feature. The 17-50mm retails for $649, and features a zoom lock, an auto/manual focus switch, and includes the flower-shaped lens hood. For more detailed specifications, see below (click for large view):

Betsy Finn, CPP, is a photographic artist and a PPA Councilor (’09-’12). Her educational website for photographers is learnwithbetsy.com.